ArF Resist Composition for Low LWR and MEEF
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Solution Overview
Problem
Existing resist materials for ArF excimer laser lithography suffer from significant line width roughness (LWR), which affects the performance of semiconductor devices, and attempts to reduce LWR often exacerbate mask error enhancement factor (MEEF) issues, making it difficult to achieve both minimal LWR and improved MEEF simultaneously.
Innovation Solution
A positive resist composition comprising a polymer with specific recurring units, including acid labile group-protected lactone units and lactone units, which are incorporated in specific ratios to enhance solubility in alkaline developers and control acid diffusion during post-exposure baking, thereby reducing LWR and improving MEEF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a resin with lower molecular weight and/or a photoacid generator which generates a more mobile acid is used to reduce line width roughness, then LWR is improved, but MEEF is extremely exacerbated
Solution Approach 1:
The patent changes the chemical structure parameters of the resin by introducing specific recurring units with acid labile groups and lactone units in defined ratios. This modifies the resin's molecular characteristics to achieve both low LWR and acceptable MEEF, resolving the contradiction between line width smoothness and mask error sensitivity.
Solution Approach 2:
The patent uses a composite resin system combining multiple recurring units (acid labile group-protected units and lactone units) in a copolymer structure. This composite approach allows the material to exhibit both smooth line width formation and reduced mask error enhancement, overcoming the limitations of single-component resins.
2Shape
If a resin with lower molecular weight is used to achieve smooth side walls, then side wall smoothness is improved, but exposure dose dependency and pattern density dependency are exacerbated
Solution Approach 1:
The patent optimizes the molecular weight and chemical composition parameters of the resin by incorporating specific recurring units in controlled ratios. This achieves smooth side walls while maintaining stable exposure dose response and pattern density characteristics, resolving the contradiction between side wall quality and process stability.
Solution Approach 2:
The patent introduces local structural features through specific recurring units (acid labile groups and lactone units) at particular positions in the polymer chain. This creates localized functional zones that promote side wall smoothness while maintaining overall process stability and reducing dose and density dependencies.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resist composition effectively forms patterns with good mask fidelity and minimized LWR, achieving precise micropatterning while maintaining excellent MEEF performance, even under high-energy radiation exposure.
Implementation Method 1
control acid diffusion during post-exposure baking
Implementation Method 2
a compound capable of generating an acid in response to actinic light or radiation
Implementation Method 3
a resin component which becomes soluble in an alkaline developer under the action of an acid
Data Source
AI summary
A positive resist composition comprises (A) a resin component which becomes soluble in an alkaline developer under the action of an acid and (B) an acid generator. Resin component (A) is a polymer comprising recurring units of formula (1) wherein R1 is H, CH2 or CF3, R2 is an acid labile group, R3 is H or CO2CH3, X is O, S, CH2 or CH2CH2, 0.01≦a<1 and 0.01≦b<1. When processed by ArF lithography, the composition forms a pattern with a satisfactory mask fidelity and a minimal LWR.